1. Field of the Invention
The invention relates to an apparatus for forming, from a metallic workpiece, a metallic unit having a concave portion bounded by a peripheral edge having a predetermined shape. More specifically, the invention relates to such an apparatus which is adapted to mount a tool comprising a wall-like structure having a bottom edge which defines a shape, the shape corresponding with the predetermined shape.
2. Description of Prior Art
Apparatus for forming metallic units are known in the art as illustrated in, for example, U.S. Pat. No. 3,934,441, Hamilton et al, Jan. 27, 1976, U.S. Pat. No. 4,516,419, Agrawal, May 14, 1985 and U.S. Pat. No. 4,409,809, Buchanan, Oct. 18, 1983.
The Hamilton et al patent teaches an apparatus which uses a fluid, e.g. air, under pressure to form a metallic part. However, in the Hamilton et al patent, the part is formed in a die 18 which is in the desired shape of the part. The Agrawal patent teaches a similar arrangement wherein the workpiece 18 is formed into the shape of the cavity 24 of the die 22.
In the Buchanan patent, an upper platen 1 has a downwardly extending peripheral wall 2 to define a first chamber 3. A lower platen 6 includes upwardly extending annular wall 10 which, together with platen 6, defines a chamber 13. The lower platen 6 is carried on rams 7 which move the lower platen 6 towards the upper platen 1.
A male mold 20 is secured on a table 18 which is carried on rams 16 of hydraulic motor 17. In operation, hydraulic motors 8 are started to move the ram 7 upwardly so that platen 6 is moved towards platen 1. A workpiece 21 is clamped between plates 4 and 11, and air under pressure is allowed into chamber 13 to force the workpiece 21 into the shape shown in FIG. 2.
Buchanan then goes on to form the workpiece 21 into the shape of the mold or die 20, as shown in FIGS. 3 and 4. However, it is noted that Buchanan uses a die but does not use a tool for the forming of the metallic units. Further, the two above-discussed references also use dies but not tools for forming metallic units.